An image sensor is a part for photographing images in a device such as a portable phone camera or a digital still camera (DSC). An image sensor can be classified as a charge-coupled device (CCD) image sensor or a complementary metal oxide semiconductor (CMOS) image sensor, depending on the manufacturing process and the method of using the same.
A color photographing part for a charge-coupled device (CCD) image sensor or a complementary metal oxide semiconductor (CMOS) image sensor includes color filters, each having additive mixing primary color filter segments of red, green, and blue, and the colors are separated.
A recent color filter embodied in the color photographing part has a pattern size of 2 μm or less, which is 1/100th to 1/200th of the pattern size of a conventional color filter pattern for LCDs. Accordingly, increased resolution and decreased pattern residues are important factors for determining the performance of a device.
Color filters can be formed using a resist composition including a colorant (which can be in the form of a pigment dispersion), a photoinitiator, a monomer, and a binder. Currently, factors such as the types and amounts of the resist composition components are believed to impact the quality of resolution and the amount of pattern residues.
For example, in order to provide a fine pattern, the pigment dispersion solution should have a small particle diameter to minimize pattern residues when developing an image. In order to decrease the particle diameter of the pigment dispersed in the pigment dispersion solution, the pigment should have a small primary particle diameter, and the kind and amount of a dispersing agent should be considered.
Current pigments for an electron material can have a primary particle size of approximately 50 nm. Therefore, when they are dispersed, they can have a smaller dispersion particle size.
A dispersing agent is used to maintain dispersion of a pigment by introducing a functional group that can be adhered to the surface of the pigment and adjusting pigment particles to have a predetermined distance using steric hindrance effects. The dispersing agents can be classified as polyester resins, acrylic resins, modified urethane resins, polyethers, and the like. These resins can provide adequate steric hindrance to a pigment.
Accordingly, a pigment can be dispersed when the pigment has a small primary particle size and is used with a dispersing agent that adheres to the surface of the pigment to help disperse the pigment particles by steric hindrance